Cannabis use increases risk of depression
By Liz Lockhart
Extra vigilance is required by young people who are genetically vulnerable to depression when using cannabis.
It has emerged through research that smoking cannabis leads to an increased risk of developing depression. The research was carried out by Roy Otten at the Behavioural Science Institute of Radboud University Nijmegen and is published online on the Addiction Biology website.
The research states that two-thirds of the population have the gene variant that makes them sensitive to depression. It also notes that nearly 30% of 16-year-olds in the Netherlands have used cannabis on at least one occasion and 12% indicate that they have used it during the past month.
The study also suggests that the use of cannabis increases the risk of developing schizophrenia and psychosis as well as being the cause of worse performance at school.
Smoking hashish and weed were considered to increase the risk of depression but no conclusive evidence for this was previously available. Otten thinks that this is partly because his predecessors did not consider the individual genetic vulnerability to depression.
The study was conducted over a five-year period during which data was collected from 428 families each with two adolescent children.
The children answered questions each year on topics which included their behaviour and depressive symptoms. The variant of the serotonin gene, 5-HTT, responsible for increased vulnerability to developing depression was also determined. Depressive symptoms increased in the young people who used cannabis and who had a special variant of the gene.
The researchers say ‘The effect is robust. It still remains, even if you take into account a series of other variables that could cause the effect such as smoking behaviour, alcohol use, upbringing, personality and socio-economic status. Some people might think that young people with a disposition for depression would start smoking cannabis as a form of self-medication, and that the presence of depressive symptoms is, therefor, the cause of cannabis use. However, in the longer term that is definitely not the case.’
‘Although the immediate effect of cannabis may be pleasant and cause a feeling of euphoria, in the long term we observe that cannabis use leads to an increase in depressive symptoms in young people with this specific genotype.’
It is important to know what the negative effects of cannabis use could be. Although cannabis may cause an initial feeling of euphoria, for a large group of individuals, it can lead to an increase of depressive symptoms in the long term.
